There are many industrial processes which require shearing polar fluids and dispersing them throughout nonpolar fluids with which they are immiscible, followed by subsequent coalescence to separate the polar and nonpolar fluids. In the oil field, water is a polar fluid dispersed in a nonpolar, organic fluid (oil). In order to extract the connate brine dispersed in the oil, water that is less saline than the connate brine must be added and sheared to a size which will unite with the connate brine. Up to the present, the shearing has been carried out by taking a pressure drop in the mixture consisting of the added fresh water, brine, and oil to obtain the mixing and union of the brine and sheared fresh water drops.
Methods for coalescing and separating connate water from oil by electrostatic fields are well defined in the art. Representative of this art are the disclosures in Prestridge, U.S. Pat. Nos. 3,772,180 and 3,847,775. Briefly, an electrostatic field, through which the water-contaminated oil is passed, coalesces the water dispersed in the oil into larger droplets. The coalesced droplets reach the size which enables them to gravitate in separation from the oil that is flowed through the electrostatic field. The oil is removed through an outlet near the top of the vessel. The coalesced water is removed from a body of water formed by the collected droplets in the bottom of the vessel.
Warren, et al. U.S. Pat. Nos. 4,161,439 and 4,204,934 disclose some of the first work in generating electrostatic fields for the purpose of mixing polar and nonpolar fluids. In this system, the electrode spacing was varied or independent sets of electrodes were used which were powered by separate power sources. This was done in order to generate electrostatic fields of sufficient strength for dispersing and mixing, followed by fields of lesser strength for coalescing and separation. However, with this arrangement, the sustained high field strength in the mixing areas collected and held the conductive polar phase between the electrodes. This limits the operation of the system since the accumulated water in the high field strength (mixing) area inevitably forms a path of sufficient conductivity to cause shorting between the electrodes. There is a need to reduce or stop this shorting. In addition to obviating shorting, improvements are needed in the system which will further reduce a contaminant level in one of the fluids.